1. Field
Disclosed herein are crop protection compositions which can be used against unwanted vegetation and which contain, as active compounds, a combination of at least one herbicide and at least one safener.
2. Description of Related Art
Herbicides are useful for controlling unwanted vegetation, i.e. weeds, which may otherwise cause significant damage to desirable plant species such as crop plants or ornamentals. Many potent herbicides have the ability to control for full growing seasons and at low rates of application, a broad spectrum of grass and broadleaf weeds that compete with desirable plants or crops such as wheat, cotton, or corn. Unfortunately, certain potent herbicides are not tolerated by, or are phytotoxic to, a wide of desirable plants when applied at rates effective to control unwanted vegetation. For example, a large number of sulfonamide or sulfonylurea herbicides cannot thus be employed in maize, rice or cereals with sufficient selectivity. Phytotoxic side-effects become apparent on the crop plants in particular when these herbicides are applied post-emergence, and it is desirable to avoid or reduce such a phytotoxicity.
One approach to increasing the tolerance of sensitive crops to certain herbicides while maintaining broad spectrum weed control is through the use of genetically-modified crop seed lines that have tolerance to the otherwise phytotoxic herbicide. Unfortunately, high technology costs, as well as the discomfort of many consumers to the introduction of such genetically modified crops to the market, has rendered this solution of increasing the tolerance of crops to be inadequate.
It is already known to use certain herbicides in combination with certain compounds, known as “safeners” or “antidotes,” which reduce the phytoxicity of the herbicides in crop plants without correspondingly reducing the herbicidal activity against the harmful plants. Such components in combination are termed “safened.”
For example, the use of 5-phenylisoxazoline- and 5-phenylisothiazoline-3-carboxyl derivatives as safeners for herbicides from the series of the carbamates, thiocarbamates, haloacetanilides, phenoxyphenoxyalkanecarboxylic acid derivatives, sulfonylureas and the like has been mentioned in EP-A-509433.
EP-A-520371 mentions, inter alia, 5-alkylisoxazoline- and -isothiazoline-3-carboxyl derivatives as safeners for a range of classes of herbicides.
WO92/03053 mentions the use of substituted 3-arylisoxazoine- and -isothiazoline-5-carboxyl derivatives as safeners for certain herbicides. WO 91/18907 describes silyl-substituted isoxazolines, isoxazoles, isothiazolines and isothiazoles as crop protecting agents.
U.S. Pat. No. 5,516,750 mentions that compounds from the group of 5,5-disubstituted isoxazolines are outstandingly suitable for protecting crop plants against the damaging effects of aggressive agrochemicals, in particular herbicides.
However, in practice, the use of the herbicidal compositions mentioned in these publications is frequently associated with one or more disadvantages. For example, the herbicidal activity of the known compounds is not always sufficient, or, if the herbicidal activity is sufficient, then undesired damage to the useful plants can be observed.
U.S. Pat. No. 6,855,667 mentions the use of certain aromatic phosphate esters and thioesters as safeners for the herbicide clomazone. While other herbicides are mentioned in the disclosure, the only herbicide specifically exemplified is clomazone, and the only test results were on corn and cotton seeds; no results are provided for post-emergence application. Moreover, the only test results provided were for a single safener, dietholate, and the largest percent reduction in injury obtained was only 80.0%. This latter value was obtained by applying the safening compound to seeds as a seed treatment, and then later applying clomazone. The average reduction in injury reported in the patent was only 33.35% for cotton seed treatment and only 36.8% for both types of corn seed tested.
In view of the above, there remains a need in the art to provide herbicidal compositions having better properties than those described above.